Checking voltage

Checking voltage is one of the most basic useful functions of a multimeter when it comes to making sure the engine will start. Set the meter to the DC symbol and place the red probe on the positive battery terminal and the black on a negative terminal. If you get the terminals the wrong way round on a digital meter you will see a minus sign and on an analogue meter the pointer goes away from the scale. Note a normal battery with a healthy state of charge (say 70%) should read about 12.5V and if it’s barely 12V or less it’s nearly flat. For an accurate test the battery should have been at rest for a couple of hours, i. since the engine was running. When the engine is running expect the charging circuit to be delivering something like 13.5V or more.